3  * coupled.c - helper functions to enter the same idle state on multiple cpus
40  * Once all cpus are ready to enter idle, they are woken by an smp
42  * cpus will find work to do, and choose not to enter idle.  A
47  * cpu exits idle, the other cpus will decrement their counter and
50  * requested_state stores the deepest coupled idle state each cpu
56  * and only read after all the cpus are ready for the coupled idle
62  * the waiting loop, in the ready loop, or in the coupled idle state.
64  * or in the coupled idle state.
88  * struct cpuidle_coupled - data for set of cpus that share a coupled idle state
94  * @prevent: flag to prevent coupled idle while a cpu is hotplugging
143  * Must only be called from within a coupled idle state handler
218  * down from the number of online cpus without going through the coupled idle
286  * cpuidle_coupled_get_state - determine the deepest idle state
290  * Returns the deepest idle state that all coupled cpus can enter
323  * Ensures that the target cpu exits it's waiting idle state (if it is in it)
324  * and will see updates to waiting_count before it re-enters it's waiting idle
328  * either has or will soon have a pending IPI that will wake it out of idle,
329  * or it is currently processing the IPI and is not in idle.
362  * Updates the requested idle state for the specified cpuidle device.
382  * Removes the requested idle state for the specified cpuidle device.
405  * this cpu as waiting just before it exits idle.
422  * the interrupt didn't schedule work that should take the cpu out of idle.
461  * all the other cpus to call this function.  Once all coupled cpus are idle,
466  * interrupts while preparing for idle, and it will always return with
511 	 * Wait for all coupled cpus to be idle, using the deepest state  in cpuidle_enter_state_coupled()
551 	 * All coupled cpus are probably idle.  There is a small chance that  in cpuidle_enter_state_coupled()
554 	 * cpu has incremented the ready counter, it cannot abort idle and must  in cpuidle_enter_state_coupled()
556 	 * another cpu leaves idle and decrements the waiting counter.  in cpuidle_enter_state_coupled()
561 		/* Check if any other cpus bailed out of idle. */  in cpuidle_enter_state_coupled()
575 	 * There is a small chance that a cpu left and reentered idle after this  in cpuidle_enter_state_coupled()
576 	 * cpu saw that all cpus were waiting.  The cpu that reentered idle will  in cpuidle_enter_state_coupled()
579 	 * controller when entering the deep idle state.  It's not possible to  in cpuidle_enter_state_coupled()
582 	 * coupled idle state of all cpus and retry.  in cpuidle_enter_state_coupled()
602 	 * that brings it out of idle will process that interrupt before  in cpuidle_enter_state_coupled()
603 	 * exiting the idle enter function and decrementing ready_count.  All  in cpuidle_enter_state_coupled()
606 	 * all other cpus will loop back into the safe idle state instead of  in cpuidle_enter_state_coupled()
616 	 * Wait until all coupled cpus have exited idle.  There is no risk that  in cpuidle_enter_state_coupled()
637  * Called from cpuidle_register_device to handle coupled idle init.  Finds the
686  * Called from cpuidle_unregister_device to tear down coupled idle.  Removes the
687  * cpu from the coupled idle set, and frees the cpuidle_coupled_info struct if
707  * cpu_online_mask doesn't change while cpus are coordinating coupled idle.
726  * cpu_online_mask doesn't change while cpus are coordinating coupled idle.